Change keyboard level include guards to pragma once (#14248)

* Change keyboard level include guards to `pragma once`

And clean up a lot of layout macros

* Oops

* Remove dangling endif

keyboards/preonic/keymaps/badger/keymap.c

@@ -14,7 +14,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 // if not REV3, just compile the default keymaps
-#ifndef REV3_CONFIG_H
+#ifndef KEYBOARD_preonic_rev3
 #include "../default/keymap.c"
 #else